Specifications
1733-1/853/854
Disk
Drive
Contro
lIer
Status
Bits
0=1
1=1
2=1
3=1
4=1
6-14
Status
Ready
Busy
Interrupt
On
cylinder
End-of-
operation
Description
The selected unit
is
available and
ready to operate.
The
unit be-
comes not ready for the follow-
ing reasons:
• The disk pack is not
in
the
drive unit
• The
disk
drive motor is not
up
to opera ting speed
(2400
rpm).
• The read/write heads are
not
in
the operating posi-
tion.
• A fault condition develops
in
the selected unit
The ready 'status condition is
affected
by
the operating pro-
gram only if it selects a non-
existing device or a device
that
is
not ready. Normally, this
status bit indicates that manual
intervention
is
required
at
the
selected drive unit.
The
busy
status indicates that
the controller and/or
the'
drive
unit is presently involved
in
the
performance of an operation.
Bit 1
is
set
by
the acceptance of
a load address, write, read, com-
pare, checkword
checK,
or write
address function.
The interrupt status indicates
that a selected interrupt condi-
tion has occurred. The bit is
cleared
by
the acceptance of any
output function.
The on-cylinder status bit is
set
when
the selected drive unit
positioner
is
on
cylinder. The bit
is cleared
if
the drive unit is
presently positioning or if a seek
error is detected
The end-of-operation status bit
is
set
whenever the controller
portion of
an
operation is com-
plete.
(The
busy
status
may
remain
set
if the selected unit is
positioning.) This bit
is
cleared
by
any output function.
Status
Bits
5=1
6=1
7=1
8=1
9=1
10=1
Status
Alarm
No
compare
Protected
Check
word
error
Lost data
Seek error
Description
Indicates
that
one of the follow-
ing abnormal conditions oc-
curred:
Not ready
Check word error
Lost data
Seek error
Address error
Defective track
Storage parity error
Protect fault
Bit 5 is cleared
by
any output
function.
The
not ready condi-
tion can be changed
by
selecting
another drive unit or
by
manual
intervention
at
the selected
drive unit.
Bit 6
set
indicates
that
the data
received from computer core
storage does not' compare with
data read from file storage dur-
ing a compare operation. The bit
is cleared
by
any output func-
tion.
A selected drive unit is pro-
tected and may only
be
accessed
by
protected computer instruc-
tions.
When
bit 7 is set,
it
can
be cleared
by
a protected direc-
tor function
that
has the release
bit
set
in
A.
The controller logic has detected
an incorrect checkword
in
data
read from file storage during a
read, compare, or checkword
check operation. This bit is
cleared
by
any output function.
The direct access
bus
of the
computer has not been able to
keep
up
with the file data trans-
fer
rate
during a write, read, or
compare operation. The bit is
cleared
by
any output function.
The drive unit has detected a
head positioner
that
has moved
beyond the legal limits of the
device during a load address,
write, read, compare, checkword
check, or write address function.
96769450
A